The problem can be corrected by upgrading the affected package to
version 0.97.3-1ubuntu1.1 (for Ubuntu 5.04), or 0.99.1-1ubuntu1.1 (for
Ubuntu 5.10). In general, a standard system upgrade is sufficient to
effect the necessary changes.

Details follow:

Paul Jakma discovered that Quagga's ripd daemon did not properly
handle authentication of RIPv1 requests. If the RIPv1 protocol had
been disabled, or authentication for RIPv2 had been enabled, ripd
still replied to RIPv1 requests, which could lead to information
disclosure. (CVE-2006-2223)

Paul Jakma also noticed that ripd accepted unauthenticated RIPv1
response packets if RIPv2 was configured to require authentication and
both protocols were allowed. A remote attacker could exploit this to
inject arbitrary routes. (CVE-2006-2224)

Fredrik Widell discovered that Quagga did not properly handle certain
invalid 'sh ip bgp' commands. By sending special commands to Quagga, a
remote attacker with telnet access to the Quagga server could exploit
this to trigger an endless loop in the daemon (Denial of Service).
(CVE-2006-2276)